Small internal combustion engines are used in a wide variety of applications including for example, lawn mowers, lawn tractors, snow blowers and power machinery. It is common to find that such internal combustion engines employ a carburetor to provide an appropriate air/fuel mixture (also called “charge”) to the combustion chamber of the internal combustion engine. Frequently, the carburetor in such an internal combustion engine is connected via a supply line to a fuel tank that stores fuel such as gasoline, diesel fuel and other types of liquid fuels that are used by the particular engine. Typically, fuel enters the carburetor at least in part due to a pressure differential between the fuel tank and the venturi region of the carburetor. The fuel is mixed with air within the venturi region of the carburetor.
When situated within a fuel tank, certain amounts of a liquid fuel typically become vaporized as hydrocarbons, particularly when the temperature within the tank rises, when the tank experiences high levels of jostling, and/or when the volume within the tank unoccupied by fuel (and filled with air) becomes rather large relative to the overall tank. The vaporization of fuel continues even during the normal course of storage of the fuel within the fuel tank.
Fuel vapors emanating from the fuel tanks of internal combustion engines are a primary contributor to overall evaporative emissions from such engines. Such emissions from fuel tanks can occur particularly when passage(s) are formed that link the interior of the fuel tank with the outside atmosphere, for example, passages that are provided for venting purposes as well as the passage existing between the interior of the fuel tank and the outside atmosphere when refueling occurs. Because fuel vapors can contribute to ozone and urban smog and otherwise negatively impact the environment, increasingly it is desired that these evaporative emissions from fuel tanks be entirely eliminated or at least reduced.
In particular, legislation has recently been enacted (or is in the process of being enacted) in various jurisdictions such as California placing restrictions on the evaporative emissions of Small Off Road Engines (SORE), such as those employed in various small off-road vehicles and other small vehicles that are used to perform various functions in relation to the environment, for example, lawn mowers and snow blowers. Additionally, the EPA is requiring that running losses be controlled on small gasoline engines.
In at least some conventional evaporative emissions control systems, carbon canisters are used to filter/adsorb fuel vapors. Yet carbon canisters are often costly additions to engines and engine applications/customer units.
For at least these reasons, therefore, it would be advantageous if an improved system (or apparatus or device) and/or method could be created to eliminate, prevent, or at least reduce evaporative emissions from fuel tanks, such as the fuel tanks of internal combustion engines including, for example, SORE engines.